1. Field of the Invention
The present invention relates to side sealing of covers consisting of a number of paper sheets, particularly to prepare for mailing.
In the following description specific reference shall be made to mailers, i.e. mail shipping covers or parcels and, it should not be construed in a limiting sense about the scope of the present invention, since the sealed covers produced by the method and apparatus of the present invention may be provided for different uses.
2. Description of the Prior Art
It is known that, besides the normal mailing system in which the printed matter in the form of sheets which is to be mailed is enclosed into an envelope which in turn is sealed either totally or partially at an open side for the introduction of the aforesaid printed matter, different systems have heretofore been proposed and adopted especially in connection with the exceedingly wide and capillary diffusion of the so-called continuous forms and of the fast printing, for example in laser printing centers.
In this case, as a matter of fact, the form is also called a "self-enveloping sheet" and has parts which were previously glued; when the printing has been completed, a folding is carried out according to predetermined folding lines and the sealing takes place preferably by activating the glue, for example by the provision of heat which causes the previously provided glue to be reactivated.
In this second case, obviously, it is necessary to have suitably punched and pre-glued sheets or forms, which are useful only for specific uses: typical examples are the payment forms issued from public or private companies supplying services such as phone services, electrical supply services, portable water supplies, etc.
In these cases the requirement imposed by the public mail service, namely the accessibility to the content of the covers for the possible postal inspection (as a matter of fact, usually these are mailings carried out at a special tariff) makes it unavoidable, not only to shape the punched sheet so as to fulfill this requisite, but also to use the so-called reversible glues, permitting the opening and the reclosing of the cover.
However there are several cases, which as a matter of fact are the majority, in which the printed material to be mailed consists of a paper sheet of the conventional type and size, but, in particular, those cases in which a certain number of different sheets constitutes the material to be transmitted to the addressee. In this case the only solution is still that of the conventional envelope of the above-mentioned type.
A typical example is that of the transmission of bank statements of account, which for most cases and customers, consist of a certain number of subsequent sheets. Another example consists of the transmission by the aforesaid service supplying companies of documents supporting the figures debited based on the payment of bills.
This problem is particularly serious when the documents to be transmitted (for example in the typical case of bank statements of account) are processed and printed at a very high operational rate, which in the above cited example uses computerized accounting centers and laser printers operating at a high speed (of the order of 80 cm/sec.); folding along predetermined folding lines is also carried out mechanically and is made automatic. However, the introduction of the documents into the envelopes causes the whole operation to be slowed down in an untolerable measure, sometimes making it almost superfluous and making it necessary to resort to more and more sophisticated and faster acting apparatus.
Of course, the separated envelopes cause greater expenses not only due to their intrinsic cost, but also owing to the greater weight as a result of the increased weight of the covers to be mailed and this increased weight is reflected in the mailing costs which as a matter of practice and almost universally are unequivocally dependent on the weight of the letter to be mailed.